Grinding machine



June 20, 1961 M. M. BAss ETAL 2,988,857

GRINDING MACHINE Filed Nov. 29, 1956 8 Sheets-Sheet 1 IIJ.

BY FHM/P J Pa/schlau@ 45.5

WMM www HTTORNEYS GRINDING MACHINE Filed Nov. 29, 1956 8 Sheets-Sheet 2 HTTRNE' YS' M. M. BASS ET AL June 20, 1961 GRINDING MACHINE 8 Sheets-Sheet 5 Filed Nov. 29, 1956 ATTORNEYS' M. M. BASS El' AL GRINDING MACHINE `lune 20, 1961 8 Sheets-Sheer. 4

Filed Nov. 29, 1956 HTTKNEYS June 20, 1961 M. M. BASS ETAL 2,988,857

GRINDING MACHINE Filed Nov. 29, 1956 8 Sheets-Sheet 5 Y |5 23 f/lllllllllllll I2 I I HTTORNEYS 8 Sheets-Sheet 6 M. M. BASS ET AL GRINDING MACHINE X 1MM e l Zwam w m w. ma?? E l, N Q m im@ m yz/ A m wmfwwm W.. l, fr @me M A h rw WW |16 8 7 \m\w7 @am /v/Q Q :z m j. M/ n w M m/ IT l L 3 .w il M m/ W 8 6 zal B9 7\ I l M 7 .v B W f a w. V\| ./w/J

June 20, 1961 M, M, BASS ETAL 2,988,857

GRINDING MACHINE Filed Nov. 29, 1956 8 Sheets-Sheet '7 INI/ENTORS mam Mw @W June 20, 1961 M. M. BAss Erm. 2,988,857

GRINDING MACHINE Filed Nov. 29, 195e s sheets-sneer e llllllllll l' HQI||||||||||||||||||||||||| .States Paten-t I' 12,988,857 4 GRINDING MACHJNE Miles M. Bass, Kalamazoo, Ramsay M. Bell, Schoolcrat, Lee C. Hammond, Kalamazoo, Edward C. Krueger, Otsego, and `Philip J. Robischung, Kalamazoo, Mich., assgnors t Hammond Machinery Builders, Inc., Kalamazoo, Mich., a corporation of Michigan Filed Nov. 29, 1956, Ser. No. 625,009 11 Claims. (Cl. 51-55) This `invention relates to a tool grinder and particularly to a-combined work holding, work positioning and work feeding means therefor which may be readily adapted by the operator to be fully automatic, semi-automatic or manually operated according to the type of service to be performed.

In spite ofconstant and serious attempts to improve the machinery used for grinding various types of cutting tools, relatively little success has been achieved in the development of an automatic, or substantially automatic, machine for grinding large number of identical tools. This appears to be due in part to the difficulty of rendering the tool holding mechanism of an automatic machine suiiiciently flexible to handle a Wide variety of types of tools and also capable of manual operation when the need arises. It is known that, under any circumstances, vthere are always a new tools winch do not lend themselves readily to automatic grinding either because of their peculiar shape or because of their limited number. Thus, at least `from a commercial point of view, the result has usually been that, since a few tools must almost always be handled individually and, therefore, a skilled grinding operator is necessarily present anyway for handling such individual tools, there is insufcient economy to be obtained by having an automatic machine in addition to a separate manually controlled machine. Because of this, a great amount of time is lost, particularly by manually holdingand controlling large numbers of identical tools which must receive the same grinding operation.

Accordingly, a major object 'of the present invention has been the'provision of Work holding means 'particularly intended for tool grinding but `applicable to other grinding purposes as Well, and which at the will of the operator may bereadily arranged to operate 'as a fully automatic machine, as a semiautomatic machine or 'by solely manual positioning and control of the tool.

A further object of the invention has been to provide a machine, as aforesaid, in'which the steps required to convert the machine from any one to any other of fully automatic, semi-automatic or manually controlled conditions can be carried out easily and quickly 'and can normally be carried out by the machine operator himself.

A diurtherobject of the invention has been to provide a machine, as aforesaid, which (a) When operated as an automatic machine and with any selected adjustment is capable of handlingflarge quantities of identical tools, and (b) is capable of adjustment to adapt it for handling a Wide varietyfof shapes and sizes of cutting tools.

A further object of the invention has been to provide a machine, as aforesaid, which will be provided with means for fully protecting the Wheel from damage in the event of impropers'etting of the automatic driving mechanism. j

A further object of the invention has been to provide a machine, as aforesaid, having work handling mechanism which will be adaptable to cooperation with an oscillating grinding Wheel, which is not unduly complex and 4which Will accordingly not involve eitherunreasonable original expense or unreasonable maintenance costs.

A further object of the invention has been to provide a machine, as aforesaid, in which the work handling Patented June 20, 1961 ICC 2 mechanism includes a work holding device and a work feeding device which are independent of each other in order that the Work may be mechanically held but manually fed Where desired.

A urther object of the invention has been to provide a machine, as aforesaid, which can -be readily operated by any operator accustomed to grinding tool tips on conventional grinders.

A further object of the invention is to provide a machine, as aforesaid, which will be readily adjustable to exercise a precise and automatic control over the amount of material removed by the grinding operation.

Other objects and purposes of the invention will be apparent to persons acquainted with apparatus of this general type upon a reading of the following specification and inspection of the accompanying drawings, in which:

FIGURE 1 is a front elevational view of the upper portion of a tool grinding machine embodying the invention.

FIGURE 2 is a sectional view of said tool grinding machine substantially as taken along the line II-Il of FIGURE 1.

FIGURE 3 is a sectional view taken along the line III-III of FIGURE 1.

FIGURE 4 is a sectional view substantially as taken along the line lV-IV of FIGURE l.

FIGURE 4a is an enlarged, detailed view of a fragment of'FIGURE 4.

FIGURE 5 is a sectional view taken along the line V--V of FIGURE 4.

FIGURE 6 is a sectional view taken along the line Vl-VI of FIGURE 5.

FIGURE 7 is a sectional view substantially as taken along the line VII- VII ofFI-GURE 4.

FIGURE 8 is a sectional view substantially as taken along the line VIII-VIH of FIGURE 4.

FIGURE '9 is a sectional view taken along the line .IX-IX 0f FIGURE 4.

FIGURE 10 is a sectional View substantially as taken along the line X-X of FIGURE 4,`rotated clockwise and showing a modied, table actuating device.

FIGURE l1 is a fragmentary, top plan viewofthe structure shown in FIGURE 3, and including an adjustable tooll holder. I

FIGURE l2 is a sectional View taken along the line XII--XII of FIGURE 1l, and rotated 90 clockwise.

FIGURE 13 is a sectional view of said tool holder taken along the line XIII- XIII of FIGURE l1.

FIGURE 14 is a broken, sectional view taken along the line XIV-XIV of FIGURE 13.

FIGURE 15 is a sectional view taken view taken along the line XVXV of FIGURE 13.

FIGURE 15a is a sectional view taken along the line `XVa-XVoz .of FIGURE 13 with the eccentric hnb removed.

FIGURE 16 is a plan view of the tool holder substantially as shown n'FIGURiE 11, but arranged in a dilferent position.

FIGURE 17 is a sectional View taken along the line XVII-#XVII of FIGURE 13. i

FIGURE 18 is a sectional view taken along the'line XVIII-XVIII of FIGURE 17 androtated 90 clockwise and including a portion of the work supporting table.

FIGURE 19 is a'fragmentary,ftop'plan View ofthe structure shown in FIGUR-E 11, and including a tool vpositioning device.

lFIGUREZO is a broken sectional'vie'w taken along the'line of FIGURE 19. FIGURE 21 is a sectional view taken along the'line of FIGURE 19'.

FIGURE V22 is a sectional view taken along the line 3 XXII-XXII of FIGURE 19 and rotated 90 counterclockwise.

FIGURE 213 is a fragment of FIGURE 19 with parts thereof in dilierent operating positions.

For purposes of convenience in description, the terms front, rear, upper, lower, lef right, and derivatives thereof, will have reference to the grinding machine in its normal position of operation. More specifically, front will have reference to that side of the machine appearing in FIGURE 1, which is the side normally facing the operator. Similarly, the terms vertica horizontal, derivatives thereof, and other Words importing position, will be freely used for convenience in reference and will be understood to refer to the structure as shown and in its position of normal use. However, the use of such terminology shall not imply that the structure cannot be used in other positions, nor shall it imply that the principles of the invention, as hereinafter defined, cannot be employed in modified structures having other and differing positions of normal use.

GENERAL DESCRIPTION In general, the apparatus of the present invention is normally, though not necessarily, embodied in a machine having a radially reciprocating grinding wheel of the type set forth in Patent No. 2,922,258, dated January 26, 1960. The machine of the present invention includes a table which is reciprocable toward and away from the face of said grinding wheel in a direction parallel with the axis of said grinding wheel, said table being provided with a removable holding device for iirmly and adjustably holding the work piece, normally a cutting tool, in a precisely predeterminable position with respect to the face of the grinding Wheel. A positioning device, which is cooperable with both the table and the work holding device, is provided for quickly and accurately positioning a group of substantially identical tools, upon which the same operation is to be performed, within and with respect to said holding device.

An actuating device, such as a pressure cylinder, is, in the fully automatic arrangement, mounted between the frame of the machine and the table for urging the table toward and away from the grinding wheel in said above designated direction. An adjustable control is provided for terminating the grinding operation by stopping such urging when the table reaches a predetermined position corresponding to the desired amount of grinding. Said control then returns the table to its initial position. Positive, adjustable stops determine the maximum movement of the table and protect both the table and the grinding wheel from damaging interference with each other in the event of failure of the adjustable control.

Where the machine is to be operated semi-automatically, the actuating device is replaced by resilient means which continuously urges the table away from the grinding wheel, the table being manually urged toward the grinding wheel. Where the tool to be ground is to be held entirely manually, the table is fixed in a selected position, usually closely adjacent to the grinding wheel, by a suitable brake and the work holding device is removed. The wheel, however, continues to oscillate as before so that the tool being ground still needs to be held only in one selected position on the table against the rotating and radially oscillating grinding wheel.

. DETAILED CONSTRUCTION General organization More specifically, and as shown in FIGURES l and 2, the tool grinding machine has a support frame 11 with a top plate 12, upon which is supported the pivot struc- `ture 13, which pivotally and rotatably supports the spinwithin the frame 11 for elfecting controlled oscillation and rotation of the grinding wheel 15 through the pivot structure 13 are completely disclosed and discussed in Patent No. 2,922,258. Thus, further detailed description of these elements of the grinding machine 10 is believed to be unnecessary.

A table base y16 is mounted upon the forward end of the support frame 11 for horizontal movement in a direction substantially parallel with the axis of the spindle 14. A hood 17, which surrounds the grinding wheel 15, is provided with a bottom wall 18, which is supported upon the table base 16. A pair of table support members 20 and 21 (FIGURES l, 2 and 3) are mounted upon the bottom wall 18 of the hood on radially opposite sides of the grinding wheel 15. Said support members may be, and preferably are, substantially identical to the support members disclosed in Patent No. 2,922,258. Thus, they are arranged to eiect a tilting of the work table 22 about a substantially horizontal axis 23 defined by the edge of the upper surface 24 of said table adjacent to the grinding wheel 15. The table support members 20 and 21, as well as the hood 17, are held in position with respect to the table base 16 by means of the bolts 25, which extend through the table support flanges 40 and 41 on the base 16 and said bottom wall 18 into said members.

Table recprocable support A pair of base support bars 30 and 31 (FIGURES 4 and 9) are supported at their rearward ends upon the front end of the top plate 12 of the frame 11 and extend substantially horizontally therefrom in parallel relationship with respect to each other. Said bars are given additional support with respect to the support frame 11 by means of the gussets 32 and 33, which are secured to, and extend forwardly from, said frame 11 under said bars 30 and 31. The mutually remote or outer lateral sides of the support bars 30 and 31 are provided with elongated, parallel and horizontal recesses 34 and 35, respectively. A pair of guide ways 36 and 37 are removably held within the recesses 34 and 35 by means of the set screws 38. Said guide ways 36 and 37 are provided with parallel, horizontal grooves 50 and 51 along the respectively outer surfaces thereof.

The table base 16 (FIGURE 9) is a substantially rectangular, relatively flat member, having a pair of outwardly extending, substantially co-planar table support anges 40 and 41. Said base 16 is superimposed in broken lines at 16h in FIGURE 4 to show its relation with the parts disposed below said base. 'I'he base has a pair of parallel base support flanges 26 and 27 (FIG- URES 4 and 9), which extend downwardly from the table support ilanges 40 and 41. Said flanges 26 and 27 are positioned along, and spaced from, the said outer surfaces of the support bars 30 and 31, respectively. A pair of parallel, elongated recesses 42 and 43 are provided in the opposing faces of the flanges 26 and 27, respectively, near, and substantially parallel with, the lower edges thereof. A pair of elongated guide ways 44 and 45 (FIGURES 5, y6 and 9), which may be identical to the guide ways 36 and 37, are removably held within said recesses 42 and 43 by means of set screws 46. The opposing sides of the guide ways 44 and 45 are provided with parallel grooves 47 and 48, respectively.

A plurality of bearing balls 52 (FIGURES 4 and 9), are disposed between the guide ways 44 and 36, and 45 and 37, within their respective grooves. The said guide ways 44, 45, 36 and 37, and their corresponding grooves, are so arranged that the table base 16 is supported upon the base support bars 30 and 31 entirely by the bearing balls 52, with the center plate 53 of the table base 16 extending between the flanges 40 and 41 above said support bars 30 and 31. A plurality of adjustment studs 54 (FIGURES 5 and 6) are threadedly received through the base support flange 26 to engage the adjacent, here 'the leftward, surface 55 of the guide way 44, whereby saidguide way 44 may be adjustably urged inwardly,` or rightwardly, with respect to said ange 26. lBecause of `the free-floating nature of the mounting of the table base 16 upon-the support bars 30 and 3.1 such rightward movement of the guide way 44 produces the total eifect of causing all four of the guide ways y44, 45, V36 and '37 to snugly embrace the bearing balls 52 disposed therebetween. yLock nuts 56 are provided on the lstuds 54 for holding the adjustment` thereof.

End plates, such as those shown at 57 and 58 in -FIG- URE 6, are secured, as by means of the screws 59, upon thefront and rearends of the said guide ways to retain the bearing balls 52 within the corresponding grooves in said guide ways when they are moved relative to each other. inasmuch as Vthe movement between the walls of said grooves and the bearing balls 52 is a rolling-type movement, the centers of said bearing balls will move only one-half of the relative distance moved bythe guide ways. Accordingly, the grooves 47, `48, 50 and 51 are substantially iilled with bearing balls 52, there being only enough unoccupied space in said grooves to permit a relatively short movement, such as approximately one inch, of the guide ways 344 and 545 with respect to the guide ways 36 and 37. Thus, there are adequate bearing balls within said grooves to provide the necessary support of the table base 16 upon the base support bars 30 and 31.

The extent of the forward and rearward movement of said table base 16 with respect to the support bars 30 and 31 is not necessarily equal to the amount of movement permitted by the quantity of bearing balls 52 within the grooves or races in said guide ways. As shown in FIGURES 4, 7 and 8, adjustable stop or limit devices 61 and 62 are provided at the forward ends of the base support bars 30 and 31, respectively, for selectively controlling absolutely the full forward and full rearward positions of the table base 16 with respect to the support bars 30 and 31. The rearward motion limit device 62 (FIGURES 4 and 8) is comprised of a forwardly extending bracket`63 secured to the front edge of the table base 16, by means such as the machine screw 64, and having a downwardly extending ilange 66. An adjustment bolt 65 is threadedly received through the flange 66 for engagement with the forward end of the right support bar 31. Thus, rearward movement of the bracket 63 hence the table base 16, is adjustably limited by engagement between the bolt 65 and the adjacent end of the support bar 31.

The forward motion limit device 61 (FIGURES 4 and 7) which controls the frontward movement of the table base 16 with respect to the grinding wheel V15, is comprised of an upwardly extending bar 67 secured, as by means of the ,machine screw 68, upon the front end of the left support bar 30. An adjustment bolt 69 is threadedly received through the upper end of the bar 67 and vextends toward, and is engageable with, the adjacent,

front edge of the table base 16. When said table base 16 is in a selected lfullyfrontward position, as indicated in broken lines at 16a in IFIGURE 7, the adjustment bolt 69 engages the adjacent edge of said table base and prevents further frontward motion.

As Shown in FIGURESVI and 4, the table base 16 has a frontward projection 71 disposed between the limit devices 61 and 62 and having a downwardly extending arm 72 at the frontward end thereof. The projection 71, as well as the center plate 53 (FIGURE 9) which extends rearwardly from said projection 71, is upwardly arched to form a cavity 73. An actuating device, such as the power cylinder 74, is disposed within the cavity 73, with its piston rod 75 pivotally secured to the lower -end of the arm 72 (FIGURES lfand 4). The rear end of the cylinder 74 is pivotally secured to the bracket 76 which is lmounted upon'the top plate v112 of the support frame 11. Thus, reciprocation of the table base 16 can `be effected by extension :and retraction of the piston rod 75 within the-power cylinder 74. `The opposite-ends of 6 thepower cylinder 74 are provided with conduits 77,4and 78, by means of Awhich a source 79 of pressure iluid (FIG- URES 4 and 4a) is connectedv through the control valve 80Y to thecylinder 74 in a substantially conventional inanner.

An electric switch'81 (FIGURES 4and 4a) is mounted upon the top plate 12 of the frame 11 near to, but spaced from, the rearward and rightward end of the table base 16. Said switch is connected in a conventional manner to the control valve 80 associated with the source 79 of pressure fluid, for the purpose of operating'said valve 80 and thereby reversing the ow of said uid from said source upon actuation ofsaid switch. Said switch is operated by a plunger 82 extending frontwardly therefrom between a pair of parallel, upstanding guard bars 83 and 84. A switch actuating rod 85 is rotatably mounted by a pair of supports `86 and 87 upon the right base support flange 27, so that said rod 85 is substantially co- `axially engageable at its rearward end with said plunger 82. The guard bars 83 and 84 are sufliciently close together that the actuating rod 85 cannot pass therebetween, thereby providing protectionl against over-travel of the rod 85 and resulting injury to the switch 81. The switch 81 (FIGURE 4a) may be connected to a source S of electrical energy Ythrough a starting switch 99 in a con- 'ventional manner. The rear support 86 (FIGURE 4) is a split nut, having front and rear portions 88 and 89 separated by a resilient grommet 91 and held together by a pair of adjustment screws, for the purpose of removing the backlash in the actuating rod 85. Further details regarding a split nut of this type may be found in Pate-nt No, 2,922,258. n I

The rod 85 has a calibrated, annular dial 92 (FIG- URES 1, 2 and 4) at the frontward end thereof anda spring-backed indicator 93 supported upon the lower vsurface of the bottom wall 18 adjacent to said dial 92. Said rod 85 and support 86 have left hand threads, in this particular embodiment, so that clockwise rotation of the dial 92, as appearing in FIGURE l, will cause said rod to move away from the switch 81. Thus, by proper adjustment of the dial 92 with respect to the indicator 93 (FIG- URE 2), and as a result of the antibacklash characteristie of the support 86, the actuating rod 85 can be solocated that it will engage the plunger 82 (FIGURE 4), thereby actuating the switch 81,l when the table base 16 reaches a precise, predeterminable position during rearward movement thereof. The accuracy of the switch 81, hence of this adjustment ca n be held within .0015 inch. In this particular embodiment, the rod 85 `is varranged and constructed so that it wil move axially a distance of 0.100 of an inch with -each revolution thereof. Where machine tools, such as those fabricated from compositions including carbide, are being ground, relatively small amounts of adjustment are generally ample.

Table brakeI A brake rod 95 (FIGURES l, 2 Iand 4) is rotatably supported upon the forward edge of the top plate 12 crosswise of, and just below, the actuating rod 85; Said brake rod 95 is supported by means of an inner bracket 96 (FIGURE 4), which threadedly engages said brake rod 95, and an outer bracket 97, which acts as a bearing. The leftward end of the rod 95 is engageabl-e with the right flange 27 of the table base 16. The outer, or rightward, end of the rod 95 is provided with a control knob 98 (FIGURE I) for tightening the brake rod 95 against the right ilange 27 and thereby locking said table basein position with respect to the frame 11.

Table angular support As shown in FIGURE 3 with respect to the left table support member '20, both the left and right support members are comprised of a hollow pedestal 101 having a concave, arcuate, upper surface 102, into which the convex, arcuate surface 103 of the quadrant 104 is slidably receivable for movement about the common axis ofl said convex and concave surfaces, which is the axis 23 located in the rearward edge of the table upper surface 24 adjacent to the grinding wheel 15. The quadrants 104 of the table support members 20 and 21 are slidably, but snugly, held upon their respective pedestals 101 by means,

such as a post 105, which is resiliently secured to the quadrant 104 and slidably engaged by the pedestal 101 in a manner set forth in detail in Patent No. 2,922,258.

The post 105 in the left support member 20 is provided with a bifurcated, lower end 106 which slidably engages pins 107 on a rider 108 disposed in the cavity 111 within said pedestal 101. An adjustment screw 109, which is rotatably supported upon, and extends through, the pedestal 101, is threadedly received through said rider 108. The adjustment screw 109, which etxends forwardly through the front end of the hood 17 in a direction substantially parallel with the axis of the yactuating rod 85, has a control wheel 112 on its front end, whereby said screw 109 is rotated to produce the desired amount of tilting of the table 22 in the manner set forth in detail in Patent No. 2,922,258. The table 22 has a way 115 which which extends crosswise thereof substantially parallel with the axis 23.

Tool holding device The tool holder 116 (FIGURES 11 and 12) is comprised of a rectangular base frame 117, having an outer jaw flange 118 along, and extending upwardly from, one end thereof. Said base frame is provided with a symmetrical, rectangular opening 119 (FIGURE 18) therethrough near said outer jaw. Said base frame 117 also contains a slot 121 (FIGURES 13, 14 and 18), the center line of which is located along the lengthwise axis of said base frame and communicates with the opening 119 on the side of opening 119 remote from the jaw 118. A movable jaw plate 122, having an inner jaw 123 at one end thereof, is arranged upon the base frame 117 so that said inner Iand outer jaws -are opposed to, and can be positioned substantially parallel with, each other.

As shown in FIGURES 13, 14 and 15, said jaw plate 122 has, at a point substantially spaced from the inner jaw 123, a vertical opening 124 therethrough, the upper portion of which has fiat sides 124a and 124b and semicircular ends, and is elongated crosswise of said jaw plate 122. Said opening 124 also has a portion 125 (FIGURE 15a) near its lower end, which is elongated lengthwise of said jaw plate 122, the central Vertical axes of said upper and lower portions being a single line and constituting together the axis of the opening 124. A hub 126, having an eccentric opening 127 therethrough and a flange 128 at its upper end, is received into, and is substantially equal in diameter to the width or distance between the yfiat sides 124a and 124b (FIGURE 15) of the upper portion of the crosswise opening 124. A concentric, circular washer or spacer 129 is disposed within the lower portion 125 of said opening 124 and has an outside diameter approximately equal to the width of said lower portion 125.

A sleeve 131 is slidably received through the opening 127 in said hub 126 and has a ange 132 at the upper end thereof, which rests upon the upper surface of the flange 128 on said hub 126. The lower end of said sleeve 131 extends slightly below the lower end of the hub 126 when said flange 132 is engaging said flange 128. A bolt 133 is received through the sleeve 131 and the washer 129, and extends substantially below the lower end thereof. Said bolt is fastened near its upper end by pin 130 to said sleeve 131 and is threadedly engaged at its lower end by the nut 134 (FIGURES 13 and 14). Said nut 134 has a non-circular, cross-sectional shape (FIGURE 18) which is slidably, but nonrotatably, received into the slot 121 in said base frame 117. Said nut 134 has a flange 135 on its lower end, `and said base frame 117 is undercut adjacent to the slot 121 to provide recesses 136 and 136a, into which the ange 135 is receivable.

The sleeve 131, hub 126 and washer 129 are so arranged and constructed that, when the nut 134 is firmly secured upon the bolt 133, thereby firmly gripping the frame 117 between the nut 134 and washer 129 (FIGURE 14), the hub 126 can be rotated with respect to both the sleeve 131 and jaw plate 122. Also, such rotation of the hub 126, due to its eccentricity with respect to the sleeve 131, will effect a movement of frame 117 with respect to, and parallel with, plate 122. The elongated openings 124 and 125 are arranged so that said movement of the frame 117 is in a direction lengthwise of said frame whereby the jaw 118 is moved toward and away from the jaw 123.

The jaw plate 122 is provided with a circular opening 137 (FIGURES l1, 13 and 17) between the opening 124 and the inner jaw 123, which is centered upon the lengthwise axis of said jaw plate 122, which latter is further defined by the center line of the slot 121. A anged swivel disk 138 is rotatably disposed within the opening 137 so that its flange 139 extends under the lower surface of the jaw plate 122 and into the opening 119 in said frame 117. 'Ihe lower surface of the swivel disk 138 is provided with a diametrically disposed channel 141, and the upper portion of said disk 138 is provided with a relatively narrow and elongated slot 142, which is parallel with the lengthwise extent of the channel 141 and communicates between the upper surface of said disk 138 and said channel. The portion of said disk 138 disposable within the opening 137 is provided with an annular groove 143, which has a triangular cross-section and is beveled on its upper side. A pair of adjustment pins, of which one is shown at 144 (FIG- URE 14), are disposed within suitable, co-axial openings, of which one appears at 145, which extend laterally through the jaw plate 122 to communicate with the circular opening 137 near its rearward end, and are arranged and constructed to enter into the groove 143 when the disk 138 is disposed within the opening 137. Adjustment screws 146 are threadedly received into the openings 145 for positively urging said pins 144 into said groove 143, whereby said disk 138 can be locked in place with respect to the jaw plate 122 when desired. Due to the beveled surface 147 on the upper edge of the groove 143, the pins 144 are capable of wedging the disk `138 upwardly so that its flange 139 rmly embraces 'the lower edge of the jaw plate 122 `'adjacent to the circular opening 137.

A T-shaped anchor member 148 (FIGURES 13 and `17) has its stem 149 slidably disposed within the channel 141 for movement lengthwise thereof. A stud 151 extends upwardly from, and is secured to, the stem 149 approximately midway between the ends thereof. Said stud is slidably received through the slot 142 and is threadedly engaged by a locking nut 152 at its upper end for releasably holding said stud, hence the T-member 148, with respect to the swivel disk 138. The cross-bar 153 of the T-member 148 is disposed under the stern 149 and has upwardly and inwardly sloping bevels 154 and 155 (FIGURES 13 and 18) at its opposite ends. The bevels 154 and 155 are engageable, respectively, by correspondingly beveled surfaces 156a and 157a on the gripping members 156 and 157 (FIGURE 13) located below said cross bar and supporting same. Said gripping members and said cross bar are all disposed Within the way (FIGURES 11, 12, 13 and 18) and extend under the undercut portions 158 and 159 thereof. An adjustment or tightening screw 161, having a shoulder 162, is slidably extendable through one of said gripping members 156 and threadedly engages the other gripping member 157, so that said gripping members 156 and 157 can be positively and relatively urged toward each other by means of the screw 161, whereby the T-member 148 is firmly held upon the table 22. The stud 151, nut 152, pins 144 and screws 146 serve to secure the remainder of the tool holder assembly with respect to said table 22. A calibrated 9 quadrant i163 @FIGURES 1=1 and 16) is provided upon the upper-surface ofthe jaw plate 122 adjacent to the swivel disk 188, upon -which pointers 164 are mounted for co- Operation with said quadrant 163. A lever 165 is mountvedYupon-the `hub'126forthe purposeof rotating said hub. A- tool -166 is disposable betweenthe jaws 123 and 118 of the tool holder 116.

T obl positioning device -The`tool postioner 170 (FIGURES 19 and 20) is mountable upon the work table 22 for positioning said tool-166 'withfr'es'pect tothe grinding wheel `15. The tool positioner 170 includes a Asupport block 171, which is wider than the upper portion of the way 115. `A clamping'plate 172 is disposed 4within the way 115 and extends under the undercut portions 158 and 159 thereof (FIG- URE 12). A pair of bolts 173 extend through'suitable, vertical` openings in the support block 171 and are threadedlyfengagedwith the clamping plate 172 for locking'said support block 171 `with respect to the work table 22. Said support block 171 has a substantially horizontal opening 174 crosswise thereof, in which a pivot rod 175 is rotatably and axially slidably supported. Under normal circumstances, vthe rod 175 will be substantially parallel with the axis of the spindle 14 for reasons appearing hereinafter.

vA depth spacing bar 176 (FIGURES 19, 20 and 21) is secured, `as by means of the opening 177 and set screw 178, upon the rearward end of the pivot rod 175 and is movable therewith through an arc of approximately 1180 fdegrees. Inthisparticular embodiment, such arc terminates in positions of said bar substantially parallel with the upper surface of the table 22 and on opposite sides of the pivot rod 175, as indicated in broken and solid rlines in FIGURE 20. An elevation pin 179 is slidably disposed within an opening 181 through the bar 176, said pin being crosswise of said bar 176 and said-rod 175 -and `being located between the ends of said bar. Said pin 179 is adjustably held within the opening 181 by means of a 'lock bolt 182, which is threadly received into a-lengthwise opening 183 through the bar 176 and a part of the rod `175. A lateral spacing bar 184 (FIGURES 19 and 20), `having a lengthwise slot 185 therethrough, is adjustably mounted upon the front surface of the depth spacing bar 176 near the free end thereof by means of a bolt 187, which extends through the slot 185 and is threadedly received into said bar 176.

The tool 166 is engaged by the front surface 186 (FIG- -URE 19) of the bar 176, and/or the outer, end surface 188 (FIGURE 23) of the lateral spacing bar A184, in a manner discussed in detail hereinafter, for the purpose 4of locating said tool within a'tool holder, such as that shown at 116 in FIGURES 11 and -1-2.

An adjustment knob 189 (FIGURES 19 and 22) has `a threaded opening 191 therethrough and is threadedly 'received upon the threaded frontward end 192 of the pivot rod 175. The -front end 192 of said rod is split by meansof Va lengthwise groove 193, the outer end of which groove is enlarged and internally threaded for receiving `a lock bolt 194. Means, such as a ball 195, is @provided-in said vgroove 193 at the inner, tapered end 196 lofthe enlarged portion for engagement bythe bolt 194, `whereby the front end v192 of the rod 175 is spread, therevby locking the knob 189 upon the rod 175. The parts of said `tool positioner 170 are so arranged that, when said support block 171 is mounted upon the work table 22, said depth spacing bar 176 can be moved by the `rod 175 from a position wherein its front surface A1 86 can be-disposed both rearwardly and frontwardly of the rearward edge 23 of said table 22.

ALTERNATE STRUCTURE The `power cylinder 74, shown in FIGURE 4, may be replaced quickly and easily by the rod 200 (FIGURE 10.), vwhich has a bifurcated, front end 205 pivotally OPERATION As statedpreviously, the tool grinder 10described hereinabove may be quickly and easily adapted'for `fully automatic operation, semi-automaticoperation or fullymanual operation, such interchangeability being an integral part of the structure of the machine. For a more complete disclosure of the operation of the tool grinder, its fully automatic operation will be described first.

Under normal circumstances, the tool holder or vise 116 (FIGURES 11 and'12) is first vmounted upon the upper surface 24 of the work table 22, with the crossbar l153 of the T-member 148 disposed within the way 115, between the gripping members 156 and 157. The screw 161 is then turned until the gripping members seize the bar 153,thereby locking the T-member 148 with respect to the work table 22. The bolt 133, the adjustment screws 146 and the stud nut 152 are loosened thereby permitting lengthwise movement of the jaw plate 122 with respect to the base frame 1117 and pivotal movement of both the jaw plate 122 and base frame 117 with respect to the T-member 148. Thus, the jaws 118 and 123 can be opened and closed, and then swiveled around as desired upon the Work table 22. y

Assuming, for the purposes of illustration, that the tool 166 (FIGURE 19) has its cutting edge 167 at one -end thereof and substantially perpendicular to the lengthwise extent thereof, the vise 116 will be swiveled into a .position wherein the jaws 118 and 123 are substantially transverse of the way 115. Referring to FIGURES 17 and 18, it will be seen that, since the stem 149 is disposed within the channel 141 in the disk 138, the jaw plate 122 will swivel around the disk 138. However, in order t'o swivel the jaw plate 122 into its FIGURE 1l position, the stem 149 must be substantially completely within the disk 138. Otherwise, said stem will strike the walls of the opening 119 in the frame 117. Accordingly, transverse movement of the T-member 148 (and likewise of the disk 138 and plate 122) with Arespect to the frame 117 is somewhat limited when the vise is in the FIGURE 11 position. However, since the tool 166 can itself be moved in this direction, lengthwise of the jaws 118 and 123, no problem is encountered.

When the frame 117 and T-mem-ber 1548 are in their FIGURE 18 positions with respect to the way115, transverse movement of the T-member with respect to the yframe 1717 is even further restricted. However, this is overcome by the fact that the entire vise can be moved along the way by manipulating the screw 161 (FIG- URE 11). On the other hand, the T-member 148, when -n the FIGURE 18 position, can be moved very substantially lengthwise of the frame 117, because of the combined length of the opening 119 and slot 121. Intermediate, angular positions of the frame 117 with respect to the T-member y148, as shown in FIGURE 16, will permit some lateral and some lengthwise relative movement in varying amounts, depending upon the positions of these members. After the vise 116 is properly located on the table 22, the tool 166 is then placed between the jaws 118 and 123, yafter which the base frame 117 is s'lidably moved manually with respect to the plate 122 until the jaw 118 causes the tool 166 to be engaged by the inner jaw 123. The nuts 152 and 134 are then snugged up, but not finally tightened.

Inasmuch as the initial positioning of the T-member 148 with respect to the table 22 is approximate at best, the screw 161 (FIGURES 11 and 13) is now loosened and the entire tool vise 116 is moved along the way 115 until the center line of the tool 166 substantially intersects the center of reciprocation of the grinding surface on the Wheel 15, where said wheel will be engaging said tool. The screw 161 is now tightened and it will be unnecesasry to touch it again until the particular job is complete. T he nut 152 may now be loosened on the stud 15-1 and iinal, relatively minor, adjustments made in the position of the tool 166, as indicated by the pointers 164, so that its cutting edge will be properly aligned with ,the adjacent surface of the grinding wheel 15 for the desired grinding operation, after which the nut 152 is secured in position. The bolt 133 is then firmly secured with respect to the nut 134. Because of the fact that the sleeve 131 is slightly vlonger than the hub 126, said hub can be turned with respect to, and upon, the sleeve 131, thereby effecting relative movement between the frame 1=17 and plate 122.

After `the bolt 133 (FIGURE 13) is tightened securely in position, the hub 126 is rotated by means of the lever 165 thereon so that the eocentricity of said hub causes the frame 117, hence the outer jaw 118, to move away from the jaw plate 122. This permits lengthwise movement of the tool 166 within the vise 116. The actuating rod 85 is adjusted so that it will engage the plunger 82 on the switch 81, thereby reversing the power cylinder 74 before the table 22 reaches its full rearward position, as determined by the limit device 62. The distance between the point where the switch is closed and the point at which the table reaches its said full rearward position is arranged to be in excess of the distance the table will have to move in order to cut off the desired amount of metal from the tool being ground.

The power cylinder 74 (FIGURE 4) is now energized, thereby causing the table 22 (FIGURE 2) to move rearwardly toward the grinding wheel 15 until it reaches the position where the switch 81 is closed by the actuating rod 85. When the table 22 reaches this position, the tool 166 is moved rearwardly between the jaws 118 and 123 until it touches the grinding surface of the wheel, after which said tool is irmly locked in the vise 116 by rotating the hub 126 inthe appropriate direction by means of the lever 165. The actuating rod 85 is now rotated and backed away from the electric switch 81, as indicated by the dial 92, a distance equal to the exact depth of metal to be removed from the cutting edge 167 of said tool. Thus, when the power cylinder 74 is again energized, said table 22 will move rearwardly until the desired amount of metal is removed from the tool, before the switch 81 is actuated land the urging of the table is reversed in its direction.

Ordinarily, the tool grinder is arranged for automatic operation when there are a number of substantially identical tools to be ground in substantially the same manner. Thus, having taken this time to set the tool 166 within the vise 116, it becomes advantageous to determine the poistion of the tool within said vise in such a manner that further, similar tools being held within the vise can be positioned at exactly the same location with respect to said grinding wheel.

To accomplish this, the tool positioner 170 (FIGURE 19) is mounted upon the work table 22 in the manner described hereinabove, while the table 22 is in its forward position and spaced from the grinding wheel 15. The

llock bolt 194 is loosened, thereby permitting the adjustment knob 189 to be rotated and thus advanced along vthe pivot rod 175. The bolts 173 are loosened, thereby permitting movement of the tool positioner 170 along the way 115 until the bar 176 is adjacent to the cutting edge 167. The pivot rod 175 is moved through the support 'block 171 until the front surface 186 of the bar 176 is lsnugly against the cutting edge 167 of the tool 166. The

bolts 173 are firmly tightened into the clamping plate 172,

whereby the tool positioner 170 is locked against movement lengthwise of the way 115. The adjustment knob 189 is now moved along the rod 175 until it firmly engages the adjacent side of the support block 171, thereby Aholding the depth spacing bar 176 firmly against the tool edge 167. The lock bolt 194 is then tightened, thereby 12 locking the adjustment knob in position, as desired. The tool positioner is now adjusted for positioning additional tools in the vise 116 for a similar grinding operation. l

In order to grind a tool so positioned, the depth spacing bar 176 is rotated by the rod 175 from its solid line position into its broken line position (FIGURE 20) and then moved h'ontwardly, away from any possible interference with the grinding wheel 15. The tool grinder is now in condition for eiecting a grinding of the tool 166 held within the vise 116.

The power cylinder 74 (FIGURE 4) is energized by closing the conventional starting switch 99 on the machine, thereby causing the piston rod to draw the table 22 rearwardly toward the grinding wheel. The table 22 will move in a rearward direction until the grinding operation is complete. At this point the switch 81 is actuated by the actuating rod 85, thereby reversing the flow of pressure uid through the power cylinder 74 and returning said table 22 to the forward position for reloading.

Reloading of the vise 116 (FIGURE l1) is accomplished quickly and easily by irst rotating the hub 126 by means of the lever 165 until the jaws of the vise 116 release the tool 166, which is then removed from said vise. Another tool requiring the same operation is then placed in the vise, after which the depth spacing bar 176 is again moved over into position in front of the tool and moved as far forwardly as the adjustment knob 189 will permit. The new tool 166 is then moved snugly up against the front surface 186 of the bar 176, after which the hub 126 is again rotated until the jaws of the vise 116 irmly grip and hold the new tool. The bar 176 is again moved out of its position in front of the tool, in the same manner as `described hereinabove, after which the power cylinder 74 is again energized to effect a second operation of the machine 10.

Where it becomes necessary to grind a tool having a cutting edge 167 which, for example, is substantially along its lateral side, as shown in FIGURE 23, the tool holder 116 is mounted upon the table 22 so that the jaws thereof are substantially parallel with the way 115. In such position the frame 117 (FIGURE 18) can move a substantial distance with respect to the T-member 148, toward and away from the wheel 15. For this type of grinding operation, both the depth spacing bar 176 and the lateral spacing bar 184 on the tool positioner 170 are used to position additional tools after the iirst one is properly positioned. The bolt 187 and slot y185 provide for adjustment of the bar 184. In order to position a tool within the vise 116, the jaws and stud nut 152 thereof must be loosened and the device 170 rotated into its operative position as shown in solid lines in FIGURE 20. The new tool is placed within the jaws 118 and 123 and moved leftwardly (FIGURE 23) until it engages the bar 184. The jaws are now tightened by means of the hub 126 but the stud nut 152 is still loose. Both jaws and the 1frame structure associated therewith are now moved forwardly (disk 138 sliding on stem 149) until the cutting edge 167 of the tool engages the front surface 186 of the depth bar 176, while the tool is still engaging the bar 184. The stern 149, which is disposed in the groove 141 of disk 138, prevents other than lengthwise movement of the frame structure during said movement thereof. The nut 152 is now tightened and grinding operation may be commenced.

Under some circumstances, it may be necessary or desirable to tilt the table 22 out of a substantially horizontal position. This is easily accomplished' by turning the wheel 112 (FIGURF 2 and 3), which, being secured to the adjustment screw 109, causes the post 105 to pivot with the quadrant 104 upon the pedestal 101 of the table support member 20. The table 22, which is supported upon said quadrant 104, is thus tilted, either upwardly or downwardly, with respect to the horizontal position and about the table pivot axis 23. This,

13 however, will have no material eect upon the above described operation o-f eitherA the tool vise 116 or the tool positioner 170.

It will be seen that complex angles of thecutting edge 167 on said tool 166 can be provided by tilting the table 22 and by mounting the tool holder 116 at anangle to the way 115, such as shown in FIGURE 16. As stated'above, pivotal movement ofthe vise 116 to obtain such'adjustment can be eifected by loosening the nut 152 and the adjustment screws 146, thereby permitting a rotational movement o-f the jaw plate 122 about the swivel disk 138 within the circular opening 137. If the same jaw opening will be utilized after the vise 116 is repositioned, yit is unnecessary to loosen the nut 134 on the bolt 133 during such pivotal movement of the vise 116. After the proper angular relationship is obtained, as indicated by the pointers 164 and calibrated quadrant 163 on top of the swivel disk 138 and jaw plate 122, respectively, the adjustment screws 146 and stud nut 152 are again tightened, thereby locking the tool vise 116 in the new position.

Semi-automatic operation As used herein, semi-automatic operation pertains to a .manual urging of the table 22 toward the grinding wheel `arm 72, upon which it is pivotally mounted at one end,

and the'bracket 76, in which it is slidably received Within the guide opening 202. The spiral spring 203-, which is held under'compression between the arm 72 and bracket 7'6, resiliently `resists rearward movement of the table 22 and, therefore, continuously urges said table to its frontward position.

As in the case of the fully automatic operation, i.e., the operation utilizing the power cylinder 74 described above, the tool vise 116 may be utilized for holding the tool in position during the grinding operation and the tool positioner 170 may be utilized for locating additional tools to be 4ground in substantially the same manner. However, the use of other tool holders and/ or positioners is possible without affecting the operation of the table movement. Nevertheless, the use of some type of tool vise is advantageous in semiautomatic operation. Where the tool positioner 170 is utilized, it can be coordinated with the limit device 62 (FIGURE 8) so that a predetermined amount of the tool being ground will be removed before the rearward movement of the table 22 is stopped by the limit device 62. Frontward movement of the table 22 'by the spiral spring 203 will be terminated by the limit device 61 (FIGURE 7).

Fully manual operation In the fully manual operation, neither the power cylin# der 74 nor the spring and rod arrangement 200 are used. In such case, the table 22 is positioned as desired with respect to the grinding wheel, the limit devices being released as necessary, and the table 22`then locked in a ixed Vposition with respect to the support frame 11 vby turning the brake rod 95 (FIGURES 1 and 4) until it tightly grips the right base support flange 27 on the table base y16. The tool or other work piece being ground can then be hand fed across the surface of the table 22 and against the grinding wheel in a substantially conventional manner. Neither the tool vise 116 nor the tool positioner 170 will normally be used under these conditions and may be removed if desired. However, in this' case, as well as all of the other above mentioned circumstances of operation, the grinding wheel 15 will oscillate radially of its axis in a substantially horizontal path with respect to the .table 22, thereby providing the operational advantages discussed in detail in Patent No. 2,922,258.

tion: mean's defining an elongated slot in, and extending along, the Vupper surface of said table; vise structure including a frame having a lirst jaw fixed with respectthereto, a second jaw adjustably supported upon said frame, means including an element within said slot -for releasably 'securing said s'econd jaw'with respect to said table in a selected angular relationship with the axis of said wheel, and manually operable means for effecting movement of said rst jaw toward and `avvay from said second jaw ywhile said Vvise structure is secured to said table; and a tool positioning device including a base adjustably anchored Within said slot, a rod arranged parallel with the axis of said wheel and being axially slidably supported upon said'base, an arm extending radially from said rod and means adjustably mounted on said rod for limiting the axial movement thereof in a direction toward vsaid wheel, and said arm including la surface perpendicular to a selected alignment of said jaws; whereby work received within said jaws maybe located in one .predetermined direction with respect to said table by positioning same in contact with vsaid second jaw and said work may be located in another direction with respect to said table by positioning it in contact with said surface.

2. In a tool grinding machine having a wheel `rotatable in a vertical plane and a table normally positioned in a substantially horizontal plane adjacent thereto, means for holding the work in a predetermined position with respect to said table, comprising in combination: means V-delining `an elongated slot extending through the upper 'of said wheel, and manually operable means for effecting movement of said rst jaw toward and away from said second jaw while said second jaw is secured to said table; a tool positioning device slidably and releasably -mounted within said slot and including a rod arranged :parallel with the axis of said wheel and being axially slidably supported upon said table, an arm extending radially from said rod and means adjustably mounted -on said rod for limiting the axial movement thereof in -a direction toward said wheel, and said arm including two surfaces perpendicular to each other and one of them being perpendicular to the axis of the wheel; whereby work received with in said jaws may be located in one predetermined direction with respect to said table by positioning same in contact with one of said `surfaces and said Work may be located in another direction with respect to said table by positioning it in contact with the other of said surfaces.

3. A grinding machine comprising: a grinding wheel; a work support table located adjacent said grinding wheel; a tool holding device mounted on said table, said tool holding device including a base frame resting on the base frame and said jaw plate and transverse to the plane of said table; means for releasably locking said swivel means to said table; said base frame and said jaw plate being rotatable with respect to said swivel means about an axis transverse to the plane of said table so that they may be positioned in a variety of locations on said table about the axis of said swivel means; means for releasably locking said base frame and said jaw plate to said swivel means; and means for moving said base frame and said jaw plate toward and away from each other.

4. A grinding machine according to claim 3 including means supporting said swivel means and thereby said tool holding device on said table for sliding movement with respect thereto toward and away from said grinding wheel.

S. A grinding machine comprising: a grinding wheel, a work support table located adjacent said grinding wheel, said table having an undercut slot in the upper surface thereof extending parallel with the face of said grinding wheel; an elongated, iirst bar received Within said slot and means for locking said bar in relatively xed, but releasable, position within said slot; a second bar secured to said rst bar and extending perpendicular thereto and perpendicular to the face of said grinding wheel, said second bar resting upon the upper surface of said table; a swivel disk extending upwardly from said table, said swivel disk having an elongated groove therein through which said second bar extends, said swivel disk also having an elongated slot therethrough above and communicating with said groove; a connector extending upwardly from said second bar through said groove and said last-named slot; means for releasably securing said connector to said swivel disk whereby said swivel disk may be moved with respect to said table toward and away from said grinding wheel and may be locked in adjustable position with respect thereto; a tool holding device including a pair of relatively movable jaws adapted to grip a tool therebetween; means supporting said tool holding device on said swivel disk for rotation with respect thereto; means for releasably locking said tool holding device to said swivel disk; and means for moving said jaws toward and away from each other.

6. A grinding machine comprising: a grinding wheel; a work support table located adjacent said grinding wheel, said table having an undercut slot in the upper surface thereof extending parallel with the face of said grinding wheel; an elongated first bar received within said slot and manually operable cam means for forcing said rst bar upwardly within said slot to thereby lock same in relative fixed, but releasable, position within said slot; a second bar secured to said iirst bar and extending perpendicular thereto and perpendicular to the face of said grinding wheel; said second bar resting on the upper surface of said table; a swivel disk extending upwardly from said table, said swivel disk having an elongated groove therein through which said second bar extends and having an elongated slot therethrough above and communicating with said groove; a bolt extending upwardly from said second bar through said slot and a nut for releasably securing said bolt to said swivel disk whereby said swivel disk may be moved toward and away from said grinding wheel and may be locked in adjustable position with respect thereto by tightening said nut; a tool holding device comprising a base frame resting on the upper surface of said table and having a iirst, upstanding jaw at one end thereof; a jaw plate slidably supported on said base frame and having a second, upstanding jaw thereon opposed to said first jaw; said base frame and said jaw plate being mounted on said swivel disk for rotation with respect thereto about an axis perpendicular to said table; means for releasably locking said base frame and said jaw plate to said swivel disk; a shaft having an eccentric peripheral surface; means rotatably mounting said shaft in one of said base frame and said jaw plate for pivotal movement about an axis perpendicular to said table; said peripheral surface being engageable with an edge on the other of said base frame and jaw plate whereby rotation of said shaft will move said base frame and said jaw plate with respect to each other to thereby open and close said jaws.

7. A grinding machine comprising: a rotatable grinding wheel; a table positioned adjacent said grinding wheel, said table having a slot in the upper surface thereof extending parallel with the face of said grinding wheel; a workpiece positioning device slidably received in said slot and means for securing said workpiece positioning device in adjustable, ixed position within said slot, said workpiece positioning device including a block resting on the upper surface of said table; a rod rotatably supported in said block and extending therefrom toward said face of said grinding wheel, said rod being rotatable about an axis substantially parallel with the axis of rotation of said grinding wheel; means for moving said rod axially toward and away from said face of said grinding wheel; a bar secured to said rod and extending transverse thereto parallel with said face of said grinding wheel and being rotatable with said rod; means for limiting rotation of said rod through an arc of limited extent for positioning said bar in a tirst position for properly locating a workpiece with respect to said face of said grinding wheel and for positioning said bar -in a second position remote from the workpiece.

8. A grinding machine according to claim 7 including a spacing bar adjustably secured to the surface of said arm remote from said grinding wheel and having an edge extending transverse to said arm adjacent the end thereof remote from said rod whereby the edge of a workpiece may be positioned with respect to said grinding wheel by placing same at the juncture of said arm and said edge when said arm is in said irst position.

9. A work holding device for a grinding machine having a grinding Wheel and a work support surface located adjacent to said grinding wheel comprising: a base frame mountable upon the work support surface and having a rst jaw at one end thereof; a jaw plate slidably supported on said base frame and having a second jaw opposed to said iirst jaw; swivel means extending through said base frame substantially perpendicular to said work support surface, said swivel means being connected to said jaw plate; means for releasably locking said swivel means with respect to said support surface, said base frame and said jaw plate being movable with respect to said swivel means aroundv an axis substantially perpendicular to the support surface for positioning thereof in a variety of locations with respect to said support surface around said axis; means for releasably locking said base frame and said jaw plate with respect to said swivel means; and means for moving said base frame with respect to said jaw plate and said support surface transversely of said axis when said swivel means is locked to said Support surface and said jaw plate is locked to said swivel means, whereby said first jaw is moved toward and awayV from said second jaw.

l0. A work holding device for a grinding machine having a grinding wheel and a work support table located adjacent to said grinding wheel, comprising: a base frame for resting upon the upper surface of said table and having a iirst upstanding jaw thereon; a jaw plate slidably supported on said base frame and having a second upstanding jaw opposed to said iirst jaw; swivel means extending through said base frame substantially perpendicular to the plane defined by the upper surface of said table and pivotally connected to said jaw plate; means for releasably locking said swivel means to said table, said base frame and said jaw plate being movable with respect to said swivel means around an axis substantially perpendicular to said plane so that they may be positioned in a variety of locations on said table around said axis; means for releasably locking said base frame and said jaw plate to said swivel means; and means for moving said base frame transversely of said axis when said swivel means is locked to said table and said jaw plate is locked to said swivel means, whereby said rst jaw is moved toward and away from said second jaw.

11. In a grinding machine having a grinding wheel and -a work support table located adjacent said grinding wheel, the combination comprising: a tool holding device mountable on the work support table, said tool holding device including a base frame for resting upon the upper surface of said table and having a first upstanding jaw thereon; a jaw member slidably supported upon said base frame and having a second upstanding jaw horizontally opposed to said -rst jaw; swivel means extending through said base frame and said jaw member transversely of the plane of the surface on said table, said base frame and said jaw member being movable with respect to said swivel means around Van axis transverse of said plane of said table so that they may be positioned in a variety of locations on said table around said axis; means for releasably locking said swivel means to said table; means for releasably locking said jaw member to said swivel means; and means for selectively 18 moving said base frame transversely of said axis when said swivel means is locked to said table and said jaw member is locked to said swivel means, whereby said rst jaw is moved toward and away from said second jaw.

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